1. Field of the Invention
The present invention relates to an ion generating unit and an ion generating apparatus for use in an ion generating circuit in, for example, an air cleaner or an air conditioner.
2. Description of the Related Art
One known ion generating apparatus of this kind is described in Japanese Unexamined Patent Application Publication No. 6-181087 (Patent Document 1). As illustrated in FIG. 12, an ion generating apparatus 110 includes a housing 120, a discharge electrode 112 mounted to the front surface of the housing 120, and an opposing electrode 114. A high-voltage power supply portion 118 is disposed on the top of the housing 120. The high-voltage power supply portion 118 incorporates a high-voltage generating circuit for applying an alternating-current high voltage between the discharge electrode 112 and the opposing electrode 114.
The discharge electrode 112 includes a plurality of sawteeth 112a. The discharge electrode 112 and the opposing electrode 114 are perpendicular to each other. The opposing electrode 114 is fixed to a seat portion 120b of the housing 120. The opposing electrode 114 has a structure in which a metal is embedded in a dielectric ceramic material. The discharge electrode 112 and the opposing electrode 114 generate ozone by discharge and convert air into negative ions by using an applied alternating voltage.
However, it is necessary for the known ion generating apparatus 110 to apply a high voltage of −5 kV to −7 kV to the discharge electrode 112 in order to generate negative ions. This requires a complicated power-supply circuit and insulation structure, so that a problem of the high cost of manufacturing the ion generating apparatus 110 arises.
When a high voltage of −5 kV to −7 kV is applied to the discharge electrode 112, ozone is produced concomitantly. Therefore, it is impossible to selectively generate only negative ions. In addition, it is necessary to take sufficient safety measures against the high voltage applied to the discharge electrode 112.
Furthermore, because the discharge electrode 112 and the opposing electrode 114 perpendicularly face each other (i.e., have a three-dimensional structure), the occupied volume is relatively large, and thus, miniaturization of the ion generating apparatus 110 is difficult.